The invention relates generally to internal combustion engines and to both two-stroke and four-stroke engines. In the past, the crankcases of two-stroke and four-stroke engines were generally differently constructed. One difference was, in two-stroke engine construction, the employment of separate, sealed crankcase chambers for each cylinder, whereas, in four-stroke engine construction, such separate sealed crankcase chambers were generally not employed. Another difference was that, in two-stroke engine construction, mist lubricated needle bearings were generally employed to support the crankshaft, whereas, in four-stroke engine construction, pressure lubricated journal bearings were commonly employed.
Attention is directed to the following U.S. Pat. Nos.:
______________________________________ 2,067,715 Issued January 12, 1937 2,433,111 Issued December 23, 1947 3,499,425 Issued March 10, 1970 3,613,646 Issued October 19, 1971 3,973,532 Issued August 10, 1976 4,126,106 Issued November 21, 1978 4,461,251 Issued July 24, 1984 4,475,499 Issued October 9, 1984 4,538,567 Issued September 3, 1985 4,545,346 Issued October 8, 1985 4,660,513 Issued April 28, 1987 4,879,974 Issued November 14, 1989 4,907,544 Issued March 13, 1990 5,005,539 Issued April 9, 1991 5,007,382 Issued April 16, 1991 5,022,353 Issued June 11, 1991 5,036,801 Issued August 6, 1991 5,230,314 Issued July 27, 1993 5,279,269 Issued January 18, 1994 ______________________________________
Attention is directed to the following foreign patents:
______________________________________ DE 3129-609 Dated July 28, 1981 SU 0757-747 Dated August 25, 1980 ______________________________________